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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: chan.c,v 1.6 2003/10/31 13:56:14 mdw Exp $ |
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4 | * |
5 | * Channel management |
6 | * |
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7 | * (c) 1999 Straylight/Edgeware |
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8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the `fw' port forwarder. |
13 | * |
14 | * `fw' is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * `fw' is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with `fw'; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: chan.c,v $ |
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32 | * Revision 1.6 2003/10/31 13:56:14 mdw |
33 | * Fix data corruption in channel\! |
34 | * |
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35 | * Revision 1.5 2000/07/19 17:55:43 mdw |
36 | * (writechan): Pointless tweak: when the buffer is empty, reset the start |
37 | * pointer to the beginning. This saves doing slightly trickier |
38 | * @writev(2)@ calls when loading is light. |
39 | * |
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40 | * Revision 1.4 1999/08/31 17:42:49 mdw |
41 | * Use `sel_force' to avoid a `select' call between reads and writes. |
42 | * |
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43 | * Revision 1.3 1999/07/27 18:30:53 mdw |
44 | * Various minor portability fixes. |
45 | * |
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46 | * Revision 1.2 1999/07/26 23:27:52 mdw |
47 | * Minor modifications for new design. |
48 | * |
49 | * Revision 1.1.1.1 1999/07/01 08:56:23 mdw |
50 | * Initial revision. |
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51 | * |
52 | */ |
53 | |
54 | /*----- Header files ------------------------------------------------------*/ |
55 | |
56 | #include "config.h" |
57 | |
58 | #include <errno.h> |
59 | #include <stdio.h> |
60 | #include <stdlib.h> |
61 | #include <string.h> |
62 | |
63 | #include <sys/types.h> |
64 | #include <sys/time.h> |
65 | #include <unistd.h> |
66 | #include <sys/uio.h> |
67 | |
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68 | #include <mLib/alloc.h> |
69 | #include <mLib/conn.h> |
70 | #include <mLib/sel.h> |
71 | |
72 | #include "chan.h" |
73 | #include "fw.h" |
74 | |
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75 | #ifdef CHAN_DEBUG |
76 | # define D(x) x |
77 | #else |
78 | # define D(x) |
79 | #endif |
80 | |
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81 | /*----- Main code ---------------------------------------------------------*/ |
82 | |
83 | /* --- @writechan@ --- * |
84 | * |
85 | * Arguments: @int fd@ = file descriptor to write to |
86 | * @unsigned mode@ = what the descriptor is ready for |
87 | * @void *vp@ = pointer to channel block |
88 | * |
89 | * Returns: --- |
90 | * |
91 | * Use: Writes to a channel. |
92 | */ |
93 | |
94 | static void writechan(int fd, unsigned mode, void *vp) |
95 | { |
96 | chan *c = vp; |
97 | int w; |
98 | unsigned base = c->base; |
99 | unsigned len = c->len; |
100 | |
101 | /* --- Write data from my buffer --- */ |
102 | |
103 | if (len) { |
104 | |
105 | /* --- Do the write --- */ |
106 | |
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107 | D( printf("writechan %d: base = %u, len = %u; ", fd, base, len); ) |
108 | if (base + len <= CHAN_BUFSZ) { |
109 | D( printf("%u:%u", base, len); ) |
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110 | w = write(fd, c->buf + base, len); |
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111 | } else { |
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112 | struct iovec iov[2]; |
113 | iov[0].iov_base = c->buf + base; |
114 | iov[0].iov_len = CHAN_BUFSZ - base; |
115 | iov[1].iov_base = c->buf; |
116 | iov[1].iov_len = len - iov[0].iov_len; |
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117 | D( printf("%u:%u, %u:%u", |
118 | base, CHAN_BUFSZ - base, |
119 | 0, len + base - CHAN_BUFSZ); ) |
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120 | w = writev(fd, iov, 2); |
121 | } |
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122 | D( printf("; returned %d\n", w); ) |
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123 | |
124 | /* --- Sift through the results --- */ |
125 | |
126 | if (w < 0) { |
127 | if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) |
128 | return; |
129 | goto close; |
130 | } |
131 | else if (w == 0) |
132 | goto close; |
133 | else if (c->len == CHAN_BUFSZ && !(c->f & CHANF_CLOSE)) |
134 | sel_addfile(&c->r); |
135 | c->len -= w; |
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136 | c->base += w; |
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137 | } |
138 | if (c->len == 0) |
139 | sel_rmfile(&c->w); |
140 | |
141 | /* --- Close the output end if necessary --- */ |
142 | |
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143 | if (c->len == 0) { |
144 | c->base = 0; |
145 | if (c->f & CHANF_CLOSE) |
146 | c->func(c->p); |
147 | } |
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148 | return; |
149 | |
150 | /* --- Force a close if an error occurred --- */ |
151 | |
152 | close: |
153 | chan_close(c); |
154 | c->func(c->p); |
155 | } |
156 | |
157 | /* --- @readchan@ --- * |
158 | * |
159 | * Arguments: @int fd@ = file descriptor to read from |
160 | * @unsigned mode@ = what the descriptor is ready for |
161 | * @void *vp@ = pointer to channel block |
162 | * |
163 | * Returns: --- |
164 | * |
165 | * Use: Reads from a channel. |
166 | */ |
167 | |
168 | static void readchan(int fd, unsigned mode, void *vp) |
169 | { |
170 | chan *c = vp; |
171 | int r; |
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172 | unsigned base = c->base; |
173 | unsigned len = c->len; |
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174 | |
175 | /* --- Do the read --- */ |
176 | |
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177 | D( printf("readchan %d: base = %u, len = %u; ", fd, base, len); ) |
178 | if (base == 0) { |
179 | D( printf("%u:%u", len, CHAN_BUFSZ - len); ) |
180 | r = read(fd, c->buf + len, CHAN_BUFSZ - len); |
181 | } else if (base + len >= CHAN_BUFSZ) { |
182 | D( printf("%u:%u", base + len - CHAN_BUFSZ, CHAN_BUFSZ - len); ) |
183 | r = read(fd, c->buf + base + len - CHAN_BUFSZ, CHAN_BUFSZ - len); |
184 | } else { |
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185 | struct iovec iov[2]; |
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186 | iov[0].iov_base = c->buf + base + len; |
187 | iov[0].iov_len = CHAN_BUFSZ - base - len; |
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188 | iov[1].iov_base = c->buf; |
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189 | iov[1].iov_len = base; |
190 | D( printf("%u:%u, %u:%u", |
191 | base + len, CHAN_BUFSZ - base - len, |
192 | 0, base); ) |
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193 | r = readv(fd, iov, 2); |
194 | } |
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195 | D( printf("; returned %d\n", r); ) |
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196 | |
197 | /* --- Sift through the results --- */ |
198 | |
199 | if (r < 0) { |
200 | if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) |
201 | return; |
202 | goto close; |
203 | } |
204 | else if (r == 0) |
205 | goto close; |
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206 | else if (c->len == 0 && (c->f & CHANF_READY)) { |
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207 | sel_addfile(&c->w); |
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208 | sel_force(&c->w); |
209 | } |
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210 | c->len += r; |
211 | if (c->len == CHAN_BUFSZ) |
212 | sel_rmfile(&c->r); |
213 | return; |
214 | |
215 | /* --- Close the read end of the channel --- */ |
216 | |
217 | close: |
218 | c->f |= CHANF_CLOSE; |
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219 | if (!c->len && (c->f & CHANF_READY)) { |
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220 | sel_addfile(&c->w); |
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221 | sel_force(&c->w); |
222 | } |
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223 | sel_rmfile(&c->r); |
224 | } |
225 | |
226 | /* --- @chan_close@ --- * |
227 | * |
228 | * Arguments: @chan *c@ = pointer to channel |
229 | * |
230 | * Returns: --- |
231 | * |
232 | * Use: Closes down a channel prematurely. |
233 | */ |
234 | |
235 | void chan_close(chan *c) |
236 | { |
237 | if (!(c->f & CHANF_CLOSE) && c->len != CHAN_BUFSZ) |
238 | sel_rmfile(&c->r); |
239 | if ((c->f & CHANF_READY) && c->len != 0) |
240 | sel_rmfile(&c->w); |
241 | } |
242 | |
243 | /* --- @chan_dest@ --- * |
244 | * |
245 | * Arguments: @chan *c@ = pointer to channel |
246 | * @int fd@ = destination file descriptor for channel |
247 | * |
248 | * Returns: --- |
249 | * |
250 | * Use: Sets the channel's destination so it knows where to put |
251 | * data. |
252 | */ |
253 | |
254 | void chan_dest(chan *c, int fd) |
255 | { |
256 | if (c->f & CHANF_READY) |
257 | return; |
258 | sel_initfile(sel, &c->w, fd, SEL_WRITE, writechan, c); |
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259 | if (c->len || (c->f & CHANF_CLOSE)) { |
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260 | sel_addfile(&c->w); |
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261 | sel_force(&c->w); |
262 | } |
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263 | c->f |= CHANF_READY; |
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264 | } |
265 | |
266 | /* --- @chan_open@ --- * |
267 | * |
268 | * Arguments: @chan *c@ = pointer to channel to open |
269 | * @int from, to@ = source and destination file descriptors |
270 | * @void (*func)(void *p)@ = function to call on closure |
271 | * @void *p@ = argument to pass to function |
272 | * |
273 | * Returns: --- |
274 | * |
275 | * Use: Opens a channel. Data is copied from the source to the |
276 | * destination. The @to@ argument may be @-1@ if the file |
277 | * descriptor isn't known yet. |
278 | */ |
279 | |
280 | void chan_open(chan *c, int from, int to, |
281 | void (*func)(void */*p*/), void *p) |
282 | { |
283 | c->func = func; |
284 | c->p = p; |
285 | |
286 | c->base = 0; |
287 | c->len = 0; |
288 | c->f = 0; |
289 | |
290 | sel_initfile(sel, &c->r, from, SEL_READ, readchan, c); |
291 | sel_addfile(&c->r); |
292 | |
293 | if (to != -1) |
294 | chan_dest(c, to); |
295 | } |
296 | |
297 | /*----- That's all, folks -------------------------------------------------*/ |